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Sevenspotted Lady Beetle

Introduction

Ladybird is a name that has been used in England for more than 600 years for the European beetle Coccinella septempunctata. As knowledge about insects increased, the name became extended to all its relatives, members of the beetle family Coccinellidae. Of course, these insects are not birds, but butterflies are not flies, nor are dragonflies, stoneflies, mayflies, and fireflies, which all are true common names in folklore, not invented names. The lady for whom they were named was “the Virgin Mary,” and common names in other European languages have the same association (the German name Marienkafer translates to “Marybeetle” or ladybeetle).

In the USA, the name ladybird was popularly Americanized to ladybug, although these insects are beetles (Coleoptera), not bugs (Hemiptera).

Now, the word ladybird applies to a whole family of beetles, Coccinellidae or ladybirds, not just Coccinella septempunctata. We can but hope that newspaper writers will desist from generalizing them all as “the ladybird” and thus deluding the public into believing that there is only one species. There are many species of ladybirds, just as there are of birds, and the word “variety” (frequently used by newspaper writers) is not an appropriate substitute for the word “species.” Many ladybird species are considered beneficial to humans because they eat phytophagous insects (“pests of plants,” sometimes called “plant pests”), but not all eat pests of plants, and a few are themselves pests.

Description
Coccinellidae are a family of beetles belonging to the superfamily Cucujoidea, which in turn belongs to the series Cucujiformia within the suborder Polyphaga of the beetles (Coleoptera). Their relatives within the Cucujoidea are the Endomychidae (“handsome fungus beetles”) and Corylophidae (“minute fungus beetles”). Worldwide, nearly 6,000 species of ladybirds are known, of which 98 are currently reported to occur in Florida (Table 1). Some of these 98 are considered to be native, and others to be adventive (“having arrived from somewhere else and established feral populations”). Among the adventive species, some were introduced (introduced deliberately), and others are immigrants (having arrived by any means except deliberate introduction) (Frank & McCoy 1990).

Ladybird adults are oval, range in length from about 1 mm to over 10 mm depending upon species, and have wings. Females on average are larger than males. Adults of some species are brightly colored. Their mandibles are used for chewing. Adult ladybirds are able to reflex-bleed from the tibio-femoral articulations (leg joints). The blood (hemolymph) is repellent by having a repulsive smell as well as containing (in some species) various alkaloid toxins (adaline, coccinelline, exochomine, hippodamine, etc.). The hemolymph is yellow and its repellency and toxicity are believed to be a defense mechanism against predators. Some people have claimed that the bright (red on black, or black on red) colors of some adult ladybirds are aposematic, which is to say that the colors warn would-be predators that the beetles are distasteful or toxic.

The immature stages (eggs, larvae, and pupae) also contain the toxins that their adults have, and in this characteristic, they resemble rove beetles (Staphylinidae) of the genus Paederus (Frank and Kanamitsu 1987) although the toxins are totally different. Toxins are said to be produced by dorsal glands in the larvae (Dixon 2000). Eggs are elongate-ovoidal, and in just a few species are protected by secretions of the adult female. Cannibalism of eggs, larvae and pupae is common, especially when prey is scarce. Larvae are mobile, and in some species (for example of Scymnus and Cryptolaemus) are protected by waxy secretions. Pupae are unprotected by a cocoon (as in some other beetles), but larvae may wander some distance from feeding sites (where they may be at risk from cannibalism) before pupating.